Both iron deficiency (ID) and excess can lead to impaired health status. There is substantial
evidence of a U-shaped curve between the risk of adverse birth outcomes and maternal
hemoglobin concentrations during pregnancy; however, it is unclear whether those relations
are attributable to conditions of low and high iron status or to other mechanisms. We
summarized current evidence from human studies regarding the association between birth
outcomes and maternal hemoglobin concentrations or iron status. We also reviewed effects …